A bootstrap circuit is, for example, used for a word line driver for a memory, DRAM, or the like.
A word line boosting method may be used as a method for applying a voltage, which is equal to or more than a power supply voltage plus a threshold voltage, to a word line and writing a power supply voltage in a memory cell connected to the word line in order to improve noise-resistance characteristics and an operation margin of DRAM.
A semiconductor integrated circuit device may include a boost circuit. For example, in the boost circuit, an n-channel MOSFET for charging and an n-channel MOSFET for discharging may be arranged at a node to be boosted. Further, one end of a capacitor for stepping up a voltage is connected to the node to be boosted. The other end of the capacitor for stepping up a voltage is connected to a substrate bias power supply, which corresponds to a reference electric potential, via a first switch circuit. Specifically, the first switch circuit may be constituted by a flip-flop including two n-channel MOSFETs, which have their sources connected in common to the substrate bias power supply and their gates cross-connected to each other, and an n-channel MOSFET of a load. The boost circuit may also have a second switch circuit using an n-channel MOSFET. With this configuration, the node may be boosted by turning on/off the two MOSFETs constituting the first switch circuit, and thus, inverting the flip-flop.
A bootstrap circuit for providing an output voltage which is twice as large as a power supply voltage in response to a timing signal of a single input may be used in a word line driver circuit of a memory for a data processor. Specifically, an input timing signal may be supplied to gates of the first and the second FETs which are alternately turned on/off to change the state of the first and the second output nodes of the first and the second latches. Depending on the first and the second output nodes, a capacitor is charged to the power supply voltage when the third and the fourth FETs connected to a power supply are turned on. Further, an output corresponding to the sum of the power supply voltage and the charged voltage may supplied to a load when a fifth FET is turned on (with the third and the fourth FETs turned off).
A signal processing circuit which can maintain an output electric potential even after a bootstrap effect is lost may be provided. For this purpose, a resistor may be connected between an output terminal and a power supply.